I'm editing Android.mk of my project to fine-tune some compiler options. Every time the build process is started from scratch. I don't want to do a full rebuild after each and every change. Is there a way to do so?
GNU make has the option -o (http://unixhelp.ed.ac.uk/CGI/man-cgi?make) to do not remake the file file even if it is older than its dependencies, and do not remake anything on account of changes in file. Essentially the file is treated as very old and its rules are ignored.
This code does the trick:
ndk-build -o jni/Android.mk
Related
I'm trying to use add_custom_command to generate a file during the build. The command never seemed to be run, so I made this test file.
cmake_minimum_required( VERSION 2.6 )
add_custom_command(
OUTPUT hello.txt
COMMAND touch hello.txt
DEPENDS hello.txt
)
I tried running:
cmake .
make
And hello.txt was not generated. What have I done wrong?
The add_custom_target(run ALL ... solution will work for simple cases when you only have one target you're building, but breaks down when you have multiple top level targets, e.g. app and tests.
I ran into this same problem when I was trying to package up some test data files into an object file so my unit tests wouldn't depend on anything external. I solved it using add_custom_command and some additional dependency magic with set_property.
add_custom_command(
OUTPUT testData.cpp
COMMAND reswrap
ARGS testData.src > testData.cpp
DEPENDS testData.src
)
set_property(SOURCE unit-tests.cpp APPEND PROPERTY OBJECT_DEPENDS testData.cpp)
add_executable(app main.cpp)
add_executable(tests unit-tests.cpp)
So now testData.cpp will generated before unit-tests.cpp is compiled, and any time testData.src changes. If the command you're calling is really slow you get the added bonus that when you build just the app target you won't have to wait around for that command (which only the tests executable needs) to finish.
It's not shown above, but careful application of ${PROJECT_BINARY_DIR}, ${PROJECT_SOURCE_DIR} and include_directories() will keep your source tree clean of generated files.
Add the following:
add_custom_target(run ALL
DEPENDS hello.txt)
If you're familiar with makefiles, this means:
all: run
run: hello.txt
The problem with two existing answers is that they either make the dependency global (add_custom_target(name ALL ...)), or they assign it to a specific, single file (set_property(...)) which gets obnoxious if you have many files that need it as a dependency. Instead what we want is a target that we can make a dependency of another target.
The way to do this is to use add_custom_command to define the rule, and then add_custom_target to define a new target based on that rule. Then you can add that target as a dependency of another target via add_dependencies.
# this defines the build rule for some_file
add_custom_command(
OUTPUT some_file
COMMAND ...
)
# create a target that includes some_file, this gives us a name that we can use later
add_custom_target(
some_target
DEPENDS some_file
)
# then let's suppose we're creating a library
add_library(some_library some_other_file.c)
# we can add the target as a dependency, and it will affect only this library
add_dependencies(some_library some_target)
The advantages of this approach:
some_target is not a dependency for ALL, which means you only build it when it's required by a specific target. (Whereas add_custom_target(name ALL ...) would build it unconditionally for all targets.)
Because some_target is a dependency for the library as a whole, it will get built before all of the files in that library. That means that if there are many files in the library, we don't have to do set_property on every single one of them.
If we add DEPENDS to add_custom_command then it will only get rebuilt when its inputs change. (Compare this to the approach that uses add_custom_target(name ALL ...) where the command gets run on every build regardless of whether it needs to or not.)
For more information on why things work this way, see this blog post: https://samthursfield.wordpress.com/2015/11/21/cmake-dependencies-between-targets-and-files-and-custom-commands/
This question is pretty old, but even if I follow the suggested recommendations, it does not work for me (at least not every time).
I am using Android Studio and I need to call cMake to build C++ library. It works fine until I add the code to run my custom script (in fact, at the moment I try to run 'touch', as in the example above).
First of,
add_custom_command
does not work at all.
I tried
execute_process (
COMMAND touch hello.txt
)
it works, but not every time!
I tried to clean the project, remove the created file(s) manually, same thing.
Tried cMake versions:
3.10.2
3.18.1
3.22.1
when they work, they produce different results, depending on cMake version, one file or several. This is not that important as long as they work, but that's the issue.
Can somebody shed light on this mystery?
I need to build libpng, but without #define PNG_READ_eXIf_SUPPORTED in pnglibconf.h
I've read comments from pnglibconf.dfa, and here are some ways of disabling features, however I didn't manage to make what I want using them.
The problem is in that, build process is performed on build server, so I can't change any files inside of libpng submodule. Here is how server works:
Download clone sources from git
Generate makefile by running cmake ..
Run make command.
Thus I have libnpg, but with included PNG_READ_eXIf_SUPPORTED option.
Libpng is a submodule of my project, so it checked out by build server automatically so I can't change pnglibconf manually.
As it said in pnglibconf.dfa file:
There are three ways of disabling features, in no particular order:
1) Create 'pngusr.h', enter the required private build information
detailed below and #define PNG_NO_<option> for each option you
don't want in that file in that file. You can also turn on options
using PNG_<option>_SUPPORTED. When you have finished rerun
configure and rebuild pnglibconf.h file with -DPNG_USER_CONFIG:
make clean
CPPFLAGS='-DPNG_USER_CONFIG' ./configure
make pnglibconf.h
pngusr.h is only used during the creation of pnglibconf.h, but it
is safer to ensure that -DPNG_USER_CONFIG is specified throughout
the build by changing the CPPFLAGS passed to the initial ./configure
I tried to do what is written here. I run cmake .. -DCMAKE_C_FLAGS="-DPNG_USER_CONFIG -I/home/me/dev/include" where /home/me/dev/include - is a path to pngusr.h file
Then I run make command. However, PNG_READ_eXIf_SUPPORTED is still present in generated (by make command pnglibconf.h file).
So my main question is how to make libpng without PNG_READ_eXIf_SUPPORTED option?
It remains unclear to me whether and to what extent the specific customization mechanism you are trying to use works in the version of libpng you are trying to use. But it looks like there's a simpler way. Just below the excerpt you posted, in the same file, is the second (of three) alternatives:
2) Add definitions of the settings you want to change to CPPFLAGS;
for example:
-DPNG_DEFAULT_READ_MACROS=0
(lightly formatted). I'm not in a good position to test that on the CMake-based build system, but it seems to work like a charm in the Autotools build system. From examining and comparing the two, I think it will work for CMake, too. In particular, you would want to run
cmake .. -DCMAKE_CPP_FLAGS="-DPNG_NO_READ_eXIf"
for your particular case.
Note, by the way, that the CPP (i.e. preprocessor) flags are the right place for an option such as you are specifying (for -DPNG_USR_CONFIG in your original attempt, too). In practice, though, they probably still work in the C compiler flags.
I am working to enable the kexec support in my propriety Linux distribution and I would like to debug the kexec tools in user space. I am adding debug prints in the kexec.c that's located in buildroot/output/build/kexec-2.0.15/kexec/kexec.c, but if I do an incremental build with make, it doesn't look like the kexec binary has been updated. If I rebuild everything from scratch with make all, the source code kexec.c has been overridden and I don't see my changes. My guess is that every full build re-extracts the kexec package and that is why my changes are not taking affect.
How do I solve this issue?
Try to use "make kexec-rebuild".
If you only want to restart the build process of a package from its
compilation step, you can run make <package>-rebuild [...]. It will restart the compilation and installation of
the package, but not from scratch: it basically re-executes make and
make install inside the package, so it will only rebuild files that
changed.
[...]
Internally, Buildroot creates so-called stamp files to keep track of
which build steps have been completed for each package. They are
stored in the package build directory,
output/build/-/ and are named .stamp_.
The commands detailed above simply manipulate these stamp files to
force Buildroot to restart a specific set of steps of a package build
process.
(from the Buildroot manual, section Understanding how to rebuild packages -- I suggest you read the whole section)
Also, look at your build log. If you don't see a line like
>>> kexec 2.0.16 Building
then the kecxec package hasn't been (re)built.
I have a Yocto build for i.mx6 and I want to modify its Kernel. I figured that if I copy Kernel source outside the Yocto project and make my modifications without dealing with patches, I can speed things up significantly. But the thing is, the Kernel source I have to use is already patched and I want to fetch and continue working from there. I will work on the already-patched source files and re-arranging them is a painful process.
For starting point, my patches work fine, and I can get a working image using bitbake fsl-image-multimedia-full command. The Kernel source I want to use is created after this process.
I have tried copying the source under ..../tmp/work-shared/imx6qsabresd/kernel-source. Although make zImage and make modules finished without any trouble, manual building was not successful with an error in a dtsi file (Unable to parse...). Of course, I have checked the file and there was no syntax error.
Also, I checked the kernel source files I copied and it seems that the patches are successfully implemented.
Am I doing something wrong with the patches? With my manual build routine, I can build unpatched kernel source with no errors. I am sure that there are experienced Yocto users here that have their own workarounds to make this process shorter. So, any help is appreciated. Thanks in advance.
You can also edit files in tmp/work-shared/<machine>/kernel-source then compile modified kernel with bitbake -C compile virtual/kernel
My favorite method of doing kernel development in a Yocto project is to create an SDK and build the kernel outside of the Yocto system. This allows more rapid builds because make will only build new changes, whereas a kernel build within Yocto always starts from scratch.
Here are some of my notes on compiling the Linux kernel outside of the Yocto system. The exact paths for this will depend on your exact configuration and software versions. In your case, IMAGE_NAME=fsl-image-multimedia-full
Run bitbake -c populate_sdk ${IMAGE_NAME}. You will get a
self-extracting and self-installing shell script.
Run the shell script (for me it was
tmp/deploy/sdk/${NAME}-glibc-i686-${IMAGE_NAME}-cortexa9hf-neon-toolchain-1.0.0.sh),
and agree to the default SDK location (for me it was
usr/local/oecore-i686).
Source the scripts generated by the install script. I use the
following helper script to load the SDK so I don't have to keep
track of the paths involved. You need to source this in each time
you want to use the SDK.
enable_sdk.sh:
#!/bin/bash
if [[ "$0" = "$BASH_SOURCE" ]]
then
echo "Error: you must source this script."
exit 1
fi
source /usr/local/oecore-i686/environment-setup-corei7-32-${NAME}-linux
source /usr/local/oecore-i686/environment-setup-cortexa9hf-neon-${NAME}-linux-gnueabi
Copy the defconfig file from your Yocto directory to your kernel
directory (checked out somewhere outside of the Yocto tree) as
.config.
Run make oldconfig in your kernel directory so that the Linux
kernel build system picks up the existing .config.
Note: you may have to answer questions about config options that
are not set in the .config file.
Note: running make menuconfig will fail when the SDK is enabled,
because the SDK does not have the ncurses libraries set up
correctly. For this command, run it in a new terminal that has not
enabled the SDK so that it uses the local ncurses-dev packages you
have installed.
Run make -jN to build the kernel.
To run the new kernel, copy the zImage and ${NAME}.dtb files to
your NFS/TFTP share or boot device. I use another script to speed
up the process.
update_kernel.sh:
#!/bin/bash
set -x
sudo cp /path-to-linux-source/arch/arm/boot/dts/${NAME}.dtb /srv/nfs/${DEVICE}/boot/
sudo cp /path-to-linux-source/arch/arm/boot/zImage /srv/nfs/${DEVICE}/boot/
set +x
You can also point Yocto to your local Linux repo in your .bb
file. This is useful for making sure your kernel changes still
build correctly within Yocto.
SRC_URI = "git:///path-to-linux-source/.git/;branch=${KBRANCH};protocol=file"
UPDATE: Over a year later, I realize that I completely missed the question about broken patches. Without more information, I can't be sure what went wrong copying the kernel source from Yocto to an external build. I'd suggest opening a Bitbake devshell for the kernel and doing a diff with the external directory after manually applying patches to see what went wrong, or just copy the source from inside the devshell to your external directory.
https://www.yoctoproject.org/docs/1.4.2/dev-manual/dev-manual.html#platdev-appdev-devshell
When debugging certain commands or even when just editing packages, devshell can be a useful tool. When you invoke devshell, source files are extracted into your working directory and patches are applied.
Since it can't parse it, there seems to be a problem with patch. How do you patch the device tree? Are you patching it in the .bb file?
If so, check your patch for possible syntax errors, it's very easy to overlook the syntax errors in device tree. You can remove the patch and do it manually from bitbake -c devshell <kernel-name>
If not, please try to do it there and check again. Please share results if any of these helps you.
I built eng flavor of AOSP tree and installed on a device. I like to step through code of a module (say libinput.so). I want to build this module with "-O0 -g" passed as part of CFLAGS. BUT I don't want to change the Android.mk file of this module.
Lets say this module is at aosppath/frameworks/base/service/input.
I cd to this folder after sourcing build/envsetup.sh.
I tried "mm -B LOCAL_STRIP_MODULE=false". When I was stepping through eclipse gdb, I see the execution order going zig zag.
Then I tried "mm -B LOCAL_STRIP_MODULE=false LOCAL_CFLAGS="-O0 -g""
Now gdb was able to step through fine. But this doesn't seem to work in other projects. I have a module that uses skia and opengl. The build is failing when I pass LOCAL_CFLAGS on command line.
What is the suggested way to make debug flavor of specific .so or exe under AOSP tree?
Thanks
So since the main reason you don't want to make changes to Android.mk is so you don't have to check it in, an alternative here is to use the .repo/local_manifests folder to change a module that is owned by android to be owned by you.
Here is a sample my_manifest.xml file which can do this for you:
<manifest>
<remote name="origin"
fetch="ssh://git#github.com/YourRepoHere/" />
<remove-project name="platform/frameworks/base"/>
<project path="frameworks/base" remote="origin" name="frameworks-base" revision="your-branch-name"/>
</manifest>
This will remove frameworks/base from the android manifest tree, and replace it with your own manifest tree (which you need to fork into your own repository).
After that, you can then use a conditional inside of your Android.mk file like so:
ifeq ($(TARGET_BUILD_VARIANT),userdebug)
CONDITIONAL_CHANGES_HERE
endif
Again, I realize that you didn't want to modify the Android.mk file but since you also asked for the suggested way of making a module that is conditional on the build variant, I am going to include this answer anyway in case nothing better comes your way. This is really the suggested way of doing what you want to do, as your project will now be maintained by the repo tool.